Synthesis of Catalyst-Free Al Doped β-Ga₂O₃ Nanorod Arrays on Quartz Substrate by a Simple Chemical Vapor Deposition

The Al doped β-Ga2O3 (β-Ga2O3:Al) nanorod arrays with 3.14 at% Al were successfully synthesized on quartz substrate with β-Ga2O3 seed layer by using chemical vapor deposition (CVD) method. The experimental results showed that the β-Ga2O3 seed layer thickness had important effects on alignment of β-Ga2O3:Al nanorods. At the synthesized temperature of 910 °C, the β-Ga2O3:Al nanorods were random, uneven length and size on seedless layer quartz substrates, disorderly stacked together to shape on quartz substrates with 17 nm thick β-Ga2O3 seed layer and inclined nanorod arrays on quartz substrates with 91 nm thick β-Ga2O3 seed layer. The XRD, XPS and EDX measurements proved that Al was doped into nanorods and substituted for Ga atom. The optical transmittances of all β-Ga2O3:Al nanorods were above 70% in the region with wavelength greater than 276 nm and showed a sharp drop around wavelength of 250 nm. The band gap of β-Ga2O3 nanorods increased from 4.85 eV to 4.93 eV after 3.14 at% Al doping.